Understanding Chef Environment Attributes - ruby

Question

Background
I am trying to understand how to correctly work with environment attributes in recipes. Note: I understand that my approach may not be Chef's best practices; however, my goal is to understand data flow here, not to necessarily use my approach in a production application.
Some details:
I am using Vagrant and Chef -- specifically, the chef-zero
provisioner (Thus I must use ruby files for my environments rather
than JSON due to a chef-vagrant limitation).
Here is my directory structure:
├── environments
├── vm.rb
├── roles
├── base.json
├── cookbooks
├── init
├── recipes
├── default.rb
├── Vagrantfile
Here are my files
Environment: vm.rb
name "vm"
description "Configuration file for the Kukla Demo VM"
default_attributes(
custom_demo: {
title: 'My demo title',
description: 'My demo description'
))
Role: base.json
{
"name": "base",
"description": "Base VM configuration",
"chef_type": "role",
"json_class": "Chef::Role",
"default_attributes": {},
"override_attributes": {},
"run_list": ["recipe[init::default]"]
}
Recipe: default.rb
#
# Cookbook:: init
# Recipe:: default
#
# Copyright:: 2020, The Authors, All Rights Reserved.
print 'I am here!'
print node[:custom_demo]
Chef provisioner in the Vagrantfile
...
chef.nodes_path = 'nodes/'
chef.environments_path = 'environments/'
chef.roles_path = 'roles/'
chef.cookbooks_path = 'cookbooks/'
# Roles
chef.add_role "base"
...
Expected Behavior
When I run the provisioner, I expect to see the custom_demo hash printed in the chef run log. Something like:
...
==> Machine: Synchronizing Cookbooks:
==> Machine: [2020-02-07T20:37:15+00:00] INFO: Storing updated cookbooks/init/recipes/default.rb in the cache.
==> Machine:
==> Machine: - init (0.1.0)
==> Machine: Installing Cookbook Gems:
==> Machine: Compiling Cookbooks...
==> Machine: I am here! custom_demo => { :title => 'My demo title', :description => 'My demo description' }
==> Machine: Converging 0 resources
==> Machine: [2020-02-07T20:37:15+00:00] INFO: Chef Infra Client Run complete in 0.118042019 seconds
...
Actual behavior
Instead, I get:
...
==> Machine: Synchronizing Cookbooks:
==> Machine: [2020-02-07T20:37:15+00:00] INFO: Storing updated cookbooks/init/recipes/default.rb in the cache.
==> Machine:
==> Machine: - init (0.1.0)
==> Machine: Installing Cookbook Gems:
==> Machine: Compiling Cookbooks...
==> Machine: I am here!
==> Machine: Converging 0 resources
==> Machine: [2020-02-07T20:37:15+00:00] INFO: Chef Infra Client Run complete in 0.118042019 seconds
...
My Question(s):
Based on the result, I'm left with the following questions:
Is my understanding of environment attributes (and therefore) my expectation correct?
If not, what am I missing? Can environment attributes be used in this fashion?
What is the proper way to debug whether an environment is being used by chef or not?
What is the proper way to reference environment attributes in a recipe so that I achieve the expected result?

Answer 1

You are doing everything right and your expectations are correct. The only thing, you are missing, is that you do not assign the environment to the vm. For that you need to add a line in your Vagrantfile:
...
chef.nodes_path = 'nodes/'
chef.environments_path = 'environments/'
chef.roles_path = 'roles/'
chef.cookbooks_path = 'cookbooks/'
chef.environment = 'vm' # the added line
# Roles
chef.add_role "base"
...
To understand, if the node has the right environment set, you can just print out in your recipe:
p node.chef_environment
# or
p node.environment
Concerning your last question, you actually cannot reference from a recipe environment attributes. Chef collects attributes from different sources (recipe, environment, node etc.) and combines them into 1 attribute hash using precedence, so in the end you can only reference the attribute with highest precedence or with some particular precedence, but not by the attribute source (environment, node or recipe).
node[:custom_demo] # highest precedence
node.default[:custom_demo] # default precedence, ignoring override and normal